JPH0341082Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a starting device for a small engine equipped with a diaphragm carburetor.

(Prior Art) In general, a small engine equipped with a diaphragm type carburetor requires that the main fuel chamber of the carburetor be filled with fuel before starting the engine.
Therefore, conventionally, as disclosed in Japanese Utility Model Publication No. 51-43315, a manual pump was installed in the fuel passage from the fuel tank to the fuel valve, and the metering diaphragm of the carburetor was pushed up to close the fuel valve at the inlet of the main fuel chamber. A takera lever is provided that opens the overflow valve at the same time as it is forcibly opened. By operating this takera lever at the same time when operating the manual pump before starting the engine, it is possible to smoothly introduce fuel into the main fuel chamber and to prevent fuel from entering the main fuel chamber. It is configured to detect that the main fuel chamber is filled with fuel from the overflow.

In addition, in order to make it easier to start the engine, it is desirable to supply a rich mixture at the time of starting, but even if the main fuel chamber is filled with fuel, the amount of fuel supplied from the nozzle will match the operating conditions after starting. Therefore, in order to supply the desired rich air-fuel mixture to the engine, it is necessary to further limit the amount of intake air by operating the choke valve.

(Problems with the Prior Art) However, with the above-mentioned starting device, it is necessary to operate both the manual pump and the takera lever at the time of starting, which requires both hands and is cumbersome to handle. Furthermore, after filling the main fuel chamber with fuel, it is necessary to perform a choke operation in order to obtain a rich mixture for starting, and these operations are extremely troublesome.

(Purpose) The object of the present invention is to provide a small engine that does not require any special starting operation and can be started simply by recoil operation.

(Structure of the invention) The structure of the invention made to achieve the above object is to provide a diaphragm carburetor with a starting fuel passage that communicates the main fuel chamber and the intake passage, and a starting fuel passage that communicates with the main fuel chamber and the intake passage. A normally closed negative pressure valve is provided, and the negative pressure chamber of the negative pressure valve is connected to a negative pressure pump that operates in conjunction with the recoil starter of the engine.

(Function) When starting the engine, when the recoil starter is pulled, the negative pressure pump operates in conjunction with the recoil starter, and the negative pressure generated by the negative pressure pump causes the negative pressure valve to open the starting fuel passage, opening the main fuel chamber. and the intake passage.

At the same time, the engine's intake negative pressure generated in the intake passage acts on the main fuel chamber through the starting fuel passage, sucks out the air and fuel accumulated in the fuel chamber into the intake passage, and, together with the air flowing there, acts on the main fuel chamber. A rich mixture is generated and supplied to the engine.
When the pressure in the main fuel chamber becomes negative, the metering diaphragm moves upward to open the fuel valve and allow fuel from the pulsating pump to flow into the main fuel chamber, filling the chamber with fuel.

When the engine starts, the operation of the recoil starter is stopped, so the negative pressure generated by the negative pressure pump disappears, and the negative pressure valve closes the starting fuel passage, stopping the supply of starting fuel. After that, fuel is supplied from the normal nozzle.

(Example) An example of the present invention will be specifically described based on the drawings.

Fig. 1 is a side view of an engine using the starting device of the present invention, Fig. 2 is a longitudinal cross-sectional view showing a diaphragm carburetor (cross-sectional view taken along the line X-X in Fig. 1), and Fig. 3 is the same as that shown in Fig. 1. FIG. 4 is an explanatory diagram of an embodiment of the starting device of the present invention explained using a Y-Y line sectional view of FIG.

1 is a diaphragm type vaporizer. An intake passage 3 is provided in the carburetor body 2 of this diaphragm type carburetor 1.
is provided through the intake passage 3, and a throttle valve 4 faces the intake passage 3 from above so as to be movable forward and backward. The throttle valve 4
A main nozzle 5 is opened in the bottom wall of the lower intake passage 3, and the tip of a jet needle 6 that hangs down from the throttle valve 4 is inserted into the main nozzle 5. The main nozzle 5 communicates with a main fuel chamber 8 via a fuel orifice 7.

The diaphragm carburetor 1 also includes a pulsation pump 10 that is operated by the pulsation of the engine 9. This pulsating pump 10 has a suction side fuel passage 1
1. A discharge side fuel passage 12 is connected, and an intake side fuel passage 11 is connected to a connection port 14 to a fuel tank 13.
The discharge side fuel passage 12 is connected to the main fuel chamber 8 through the fuel tank.

The main fuel chamber 8 has a bottom wall formed by a metering diaphragm 15, and the inlet of the main fuel chamber 8 of the fuel passage 12 is connected to the diaphragm 15 to disconnect the fuel passage 12, that is, the pulsating pump A fuel valve 16 is provided that operates to disconnect and disconnect communication between fuel chamber 10 and main fuel chamber 8 . The fuel valve 1
A lever 18 having a support shaft 17 is disposed between the metering diaphragm 15 and the lever 18. One side of the lever 18 is connected to the fuel valve 16 around the support shaft 17, and the other side is connected to the diaphragm 16. It is connected to 15. Therefore, when a strong intake negative pressure acts on the main fuel chamber 8 through the main nozzle 5, the diaphragm 15 moves upward to introduce fuel from the pulsating pump 10 into the main fuel chamber 8 through the fuel passage 12. The fuel valve 16 is held in the open position via the lever 18. Furthermore, when the strong negative pressure in the main fuel chamber 8 disappears due to the introduction of fuel into the main fuel chamber 8, the fuel valve 16
The biasing force of the compression spring 19 engaged with the lever 18 blocks the fuel passage 12 to prevent the introduction of fuel into the main fuel chamber 8 .

A starting fuel passage 20 communicates the intake passage 3 downstream of the throttle valve 4 with the main fuel chamber 8 . A negative pressure valve 21 is provided in the middle of this starting fuel passage 20, and the negative pressure valve 21 is connected to an operating diaphragm 22.
A negative pressure chamber 23 is formed at the back of the operating diaphragm 22 , and this negative pressure chamber 23 is connected by a negative pressure passage 24 to a negative pressure pump 26 that is linked to a recoil starter 25 of the engine 9 . In addition, the negative pressure chamber 23
A spring 27 is compressed therein to provide the negative pressure valve 21 with a tendency to normally close. Further, the starting fuel passage 2
A starting air passage 28 is connected in the middle of the starting fuel passage 20, and by mixing air into the fuel flowing through the starting fuel passage 20, the fuel is made into a foamy fuel. In the embodiment shown in FIG. 3, the starting fuel passage 28 is configured to be opened and closed simultaneously with the starting fuel passage 20 by the negative pressure valve 21, but as shown in FIG. The negative pressure valve 21 is connected to the starting fuel passage 20 on the downstream side of the pressure valve 21.
It is also possible to configure the intake passage so that low-speed air is supplied from the passage 28 to the intake passage even when the intake passage is closed. The starting fuel passage 20 and the starting air passage 2
8 has jet 2 for regulating the flow rate.
9 and 30 are provided, and the starting fuel passage 20 is further provided with a check valve 31 for preventing blowback due to pulsation of intake negative pressure.

The negative pressure pump 26 is attached to a recoil starter case 34, with its operating rod 35 passing through the case 34. This operating rod 3
Reference numeral 5 denotes a starting pulley 3 disposed within the case 34.
It moves forward and backward by intermittently contacting a cam 37 formed on the outer circumferential surface of 6. On the other hand, the base end of the actuating rod 35 is connected to a pump diaphragm 38, and the pump diaphragm 38 is oscillated by the forward and backward movement of the actuating rod 35 by the cam 37 of the starting pulley 36.
The air chamber 39 formed on the opposite side of 8 is expanded and contracted. Further, passages 42 and 43 are connected to the air chamber 39 via check valves 40 and 41, respectively, and one passage 42 is connected to the negative pressure chamber 23 through a connection port 44 to the negative pressure chamber 23. and the other passage 4
3 is released to the atmosphere. Therefore, when the air chamber 39 expands due to the movement of the pump diaphragm 38, the air chamber 39 becomes in a negative pressure state, and the check valve 40 opens to suck the air in the negative pressure chamber 23 into the air chamber 39. Next, when the air chamber 39 contracts, the inside of the air chamber 39 becomes in a positive pressure state, and the check valve 41 is opened to release the air inside the air chamber 39 to the atmosphere.

45 is a rope that rotates the starting pulley 36; 46
47 is a rope handle, and 47 is a leak passage of the negative pressure chamber 23.

The operation of the embodiment configured as above will be explained.

When starting the engine, when the starting pulley 36 is rotated by pulling the rope handle 46,
Since the cam 37 intermittently contacts the actuating rod 35 of the negative pressure pump 26 during the rotation of the pulley 36, the actuating rod 35 moves back and forth each time, and the negative pressure pump 26 is driven. This negative pressure pump 26
When the negative pressure acts in the negative pressure chamber 23, the operating diaphragm 22 is sucked, and the negative pressure valve 21 attached to the operating diaphragm 22 opens the starting fuel passage 20.

At the same time, the engine's intake negative pressure generated in the intake passage 3 acts on the main fuel chamber 8 through the starting fuel passage 20, sucking out the air stagnant in the main fuel chamber 8, and fueling the main fuel chamber 8. suck it out. At this time, the fuel flowing through the starting fuel passage 20 is mixed with the air flowing in from the starting air passage 28, and the fuel is turned into foam fuel, which is ejected into the intake passage 3, and is mixed with the air flowing therethrough to form a dense mixture for starting. This generates air that is inhaled into the engine. When the pressure inside the main fuel chamber 8 becomes negative, the metering diaphragm 15 moves upward to open the fuel valve 16 to allow fuel from the pulsating pump 10 to flow into the chamber 8, filling the chamber 8 with fuel.

When the engine starts, the recoil starter 25
Since the operation of the negative pressure pump 26 is stopped, the negative pressure generated by the negative pressure pump 26 disappears, and the negative pressure valve 21 is operated by the spring 2.
The starting fuel passage 20 is closed by the biasing force of 7. After that, the engine continues to operate by ejecting fuel from the normal nozzle.

Further, in the above embodiment, an example was explained in which the present invention was applied to a diaphragm type carburetor equipped with a sliding throttle valve, but it is also possible to apply the present invention to a carburetor equipped with a butterfly type throttle valve. Needless to say.

(Effects) As detailed above, according to the present invention, when starting the engine, simply pulling the recoil starter removes the air accumulated in the main fuel chamber of the diaphragm carburetor, fills the chamber with fuel, and at the same time Since a rich mixture for starting can be supplied to the engine, manual pump operations, take-off operations, and choke operations that were required for conventional engines equipped with diaphragm carburetors can be completely omitted, making this type of engine Starting is extremely easy.

[Brief explanation of the drawing]

Fig. 1 is a side view of an engine using the starting device of the present invention, Fig. 2 is a longitudinal cross-sectional view showing a diaphragm carburetor (cross-sectional view taken along the line X-X in Fig. 1), and Fig. 3 is the same as that shown in Fig. 1. FIG. 4 is an explanatory diagram of an embodiment of the starting device of the present invention explained using a Y-Y line sectional view of FIG. 1...Diaphragm type carburetor, 3...Intake passage, 8...Main fuel chamber, 20...Starting fuel passage,
21... Negative pressure valve, 23... Negative pressure chamber, 25... Recoil starter, 26... Negative pressure pump.

Claims (1)

[Scope of utility model registration request] In an engine equipped with a diaphragm type carburetor, the diaphragm type carburetor is provided with a starting fuel passage that communicates the main fuel chamber and the intake passage, and a normally closed negative pressure valve is provided in the middle of this starting fuel passage. A starting device for an engine equipped with a diaphragm carburetor, characterized in that a negative pressure chamber of the negative pressure valve is connected to a negative pressure pump that operates in conjunction with a recoil starter of the engine.